Anyone now what the problem could be with my 2005 yamaha 225hpdi it seems like when I'm sitting in idle that the RPM's slowly drop then it will finally die. Then after it does this it is hard to start I have to wait a minute or so then it will start fine. Only way I can get around it starting sooner as when I'm cranking the motor it will try to fire but won't start unless I put it in gear while I'm trying to start it. This will only happen though about every 6th start of the boat it doesn't do this all the time. Also it seems like it is loosing some of it's top end speed. Before this problem boat would top out around 72-73mph now it struggles to hit 68mph. Also seems a little sluggish coming out of the hole. But when the boat is running above idle speed though the boat runs great. I have changed the spark plugs, air filter, ran a diagnostics test but nothing has seem to work. Any help at all would be greatly appreciated thanks in advance.